1. Field of the Invention
The present invention relates to a camera having a lens barrier unit which opens and closes accompanying the extension and retraction of a photographic lens unit, and, more particularly, the present invention relates to a lens barrier unit opening and closing mechanism for opening and closing lens barriers which cover a camera lens.
2. Description of the Related Art
Cameras having lens barrier unit for covering a front surface of a photographic lens unit are known. For example, a camera having a lens barrier unit and a moveable photographic lens unit are disclosed in Japanese Examined Patent Publications JP-B-4-49931 and JP-B-4-49932.
These known cameras are equipped with an operating member, capable of an operation for photographic preparation (camera is switched ON) and an operation for the conclusion of photography (camera is switched OFF). These known cameras are also equipped with a photographic lens unit that moves to an extended position, in response to the operation for photographic preparation, and moves to a retracted position, in response to the operation to conclude photography.
The photographic lens unit of the above-described cameras includes a lens barrier unit having a plurality of lens barriers, and which is capable of moving between a closed position, in which the lens barrier unit covers a front surface of the photographic lens unit, and an open position, in which the lens barrier unit moves away from the front surface of the photographic lens unit.
When the camera operating member is operated for photographic preparation, a barrier opening and closing unit, moving integrally with the operating member, drives the lens barrier unit to the open position.
When the camera operating member is operated for the conclusion of photography, the barrier opening and closing unit, which is coupled to the retraction operation of the photographic lens unit, drives the lens barrier unit to the closed position.
However, when the above-mentioned photographic lens unit is a high magnification zoom lens, the distance of the lens barrier unit from the camera body becomes long, to an extent that the lens barrel becomes long, making it necessary for the barrier opening and closing unit to become long.
As a result, because the barrier opening and closing unit of the above-mentioned known cameras moves integrally with an operating member disposed in the camera body, when the length of the barrier opening and closing unit becomes long, it becomes difficult for the end of the barrier opening and closing unit (connected to the lens barrier unit) to move by the same amount as the operating stroke of the operating member, due to the effect of bending. Therefore, there is a risk that opening and closing can be obstructed. To overcome this risk, prior art cameras have a barrier opening and closing member that is made thick to suppress bending, and, accordingly, the lens barrel has to become larger.
Further, a lens barrier opening/closing mechanism is known having a moving member which slides in a film feeding direction on an upper side of a film aperture. The moving member slides interlocking with a main switch of the camera. Further, a rectilinear movement lens barrel of a photographing lens is provided with a barrier rod slidable in an optical-axis direction. The barrier rod might contact the moving member. The moving member is formed with a stepped portion. When the main switch is turned ON, the moving member slides in the film feeding direction. The moving member is formed with the stepped portion, and hence the barrier rod that contacts the moving member displaces in the optical-axis direction. With the displacement of the barrier rod, the barrier provided in front of the lens barrel is opened and closed.
A portion where the moving member can be disposed is limited on the surface of the camera body. The moving member is a member for moving the barrier rod by coming into contact with the barrier rod provided in the rectilinear movement lens barrel and is therefore required to be provided on an outer periphery of the rectilinear movement lens barrel in such a position as to give no interference with the film aperture. A variety of mechanisms in addition to the moving member must be disposed upwardly of the film aperture. For example, a finder mechanism for observing an object is provided upwardly of the film aperture. Providing the camera incorporating the finder mechanism with the above-mentioned barrier opening/closing mechanism entails determining a layout so that the slidable moving member does not interfere with the finder mechanism.
Thus, it is difficult to dispose the moving member and the finder mechanism so as not to interfere with each other in a confined space above the film aperture.
Further, there has been recently known a camera using a known film that is magnetically writable and constructed to detect a timing of feeding the film and a timing of executing a magnetic writing process by use of two photo interrupters (photo reflectors). In such a camera, it is determined that the two photo interrupters are disposed upwardly of the aperture, while a magnetic head for magnetic writing is disposed downwardly of the aperture. It is therefore difficult to provide the barrier opening/closing mechanism together therewith upwardly of the aperture.
Moreover, with further down-sizing of the camera, a diameter of the lens barrel has been also reduced. The reduction in diameter of the lens barrel makes it difficult to dispose the above-mentioned barrier opening/closing mechanism in the conventional position.